On the use of Kalman filters for high-order mode rejection in PZT-based microscanners

This work discusses and compares two strategies for closed-loop control of quasi-static silicon mirrors for raster-scanning applications, actuated by thin films of lead-zirconate-titanate and with embedded piezoresistive angular displacement sensors. A first feedback control approach, based on piezoresistive readout of the device angular displacement through an integrated sensor, shows limitations related to high-order resonant modes of the mechanical structure. To overcome this issue, a feedback control scheme based on the use of a Kalman filter to estimate the angular displacement and velocity of the scanner is presented, achieving a maximum positioning error of 0.14 degrees (1.75% of a 8 degrees full-scale angular displacement), and a mean error within +/- 0.03 degrees (0.74% peak-to-peak) over 80% of the scanned trace.